My check engine light is on

O2 sensors will not cause any rough idle or misfire how do you know is code 20 and 21?

if you do the on off on off on deal with the ignition the check engine light flashes to give you the codes that are registered. it flashes once pauses then twice and pauses making it a 12, twice pause once pause making it a 21, and then it does the twice pause once again.

If you rev the engine does it backfire?

no it doesn't. it did it to me today and it almost died completely and the oil pressure light started to come on. i tapped the accelerator and it went back to normal.

You mean it back fired today?

no it has never backfired. what i meant is it was starting to sputter on me and almost died. sorry for the confusion

Do you have a distributor?

If I do it is not readily accessible. I can trace my plug wires to the back of the block, but i can't really tell what they are plugging in to.

What size engine do you have?

it's the 5.2L V8. I am thinking maybe the TPS but my multi meter has gone MIA....